The invention relates to an apparatus for metering a plurality of different liquid or pasty masses. Such an apparatus is known in diverse embodiments and is also designated as colour kitchen. Said masses are in that case paint, ink, thickening or thinning agents and the like. The masses have to be supplied in predetermined quantities, at least mutual ratios, to a receiving container. This receiving container, for instance a bucket, a can or the like, must be filled with a determined quantity of mixture. For this purpose predetermined quantities of selected masses are admitted successively into the receiving container. As soon as the receiving container is filled with all desired components in the desired quantities, a subsequent receiving container is filled in comparable manner with the constituent components. In this subsequent and other cycles the composition can differ in accordance with the composition of the finally required mixture.
After the constituent components have been placed in the receiving container, homogenization generally takes place by means of known homogenizing processes, in particular stirring and shaking.
An apparatus of said type comprises provisions for supporting containers for the masses for metering. These containers can be connected by means of flexible hoses or fixed conduits to dispensing nozzles for individual dosing in each case of a determined quantity of a relevant mass. A placed receiving container and all relevant dispensing nozzles must be mutually movable such that each dispensing nozzle can dispense mass to the receiving container. It is known for instances to fixedly dispose a container on scales and to place the relevant dispensing nozzle in each case above the receiving container by means of a movable frame.
Alternatively, a frame supporting the dispensing nozzles can be fixedly disposed, wherein the scales supporting the receiving container are movable thereunder.
The scales are of importance for dispensing a determined mass in the correct quantity. The control of the dispensing nozzles therefore takes place on the basis of this mass measurement. It is possible in principle to suffice with a mass or weight difference measurement.
In the case where the dispensing nozzles are movable relative to the storage container, use must be made of flexible conduits. The great drawback of flexible conduits is that they are subject to undesirable mechanical loads, in particular torsion, which can greatly reduce the lifespan and can cause malfunctions. Hoses are further subject to ageing. This is the reason why an embodiment is usually recommended with a fixed spatial relation between the dispensing nozzles and the storage containers, in which case fixed conduits of for instance plastic or metal can be used. In that case the scales with a receiving container thereon must be arranged displaceably relative to the nozzles. Such an arrangement does however have the drawback that the conduits connecting the electronically operating weighing device to central, fixedly disposed control means are likewise subjected to mechanical influences.
This mechanical influence can remain limited by making use of a horizontal linear x or XY mobility within limited boundaries. Such an arrangement has the drawback however that it takes a relatively large amount of time to go from one side of an array to the other, which may nevertheless occur during operation of the apparatus. Recommended in this respect is an annular arrangement of the dispensing nozzles and a corresponding annular path in which the weighing device with a receiving container thereon can move.
If desired, there may even be a movement predominantly in one direction along such a path. This is not possible however without specific measures, since the conduits providing the necessary supply of electrical energy to the weighing device and the information cables are otherwise placed under torsional stress.
It is an object of the invention to provide an apparatus which obviates all drawbacks of said techniques and is not afflicted with the limitations of the known art.
In respect of the above, the invention provides an apparatus for metering a plurality of different liquid or pasty masses such as paint, ink, thickening or thinning agents and the like to a receiving container, for instance a bucket or a can, which apparatus may include:
first supporting means for supporting containers for the masses in fixed positions;
a fixedly disposed annular frame bearing a number of dispensing nozzles controllable by fixedly disposed central control means (PLC, PC) and each individually connectable to said containers via respective conduits;
second supporting means controllable by said control means for supporting a receiving container such that this receiving container is displaceable in an annular path corresponding with the annular form of the frame and can be placed temporarily beneath a chosen dispensing nozzle for receiving mass dispensed by this dispensing nozzle;
a weighing device on which a receiving container can be placed, which weighing device can supply signals to the control means which are representative for the weight of the receiving container with its content or the change in that weight;
which control means are adjustable, for instance by means of program control, for dispensing different masses in determined quantities to successive receiving containers, for instance in successive cycles, in order to make successive mixtures of respective chosen compositions;
wherein the weighing device is disposed fixedly, is connected to the control means via cable means and supports the second supporting means, and
wherein the second supporting means are rotatably drivable round a vertical axis by means of a drive device co-acting with the second supporting means such that when a weighing is performed the drive is inactive such that no forces which can influence the weighing are exerted on these second supporting means, for instance the drive is substantially disengaged from the second supporting means.
Attention is drawn in this respect to the fact that an apparatus is known from applicant""s earlier non-prepublished Netherlands patent application NL-1006685 of Jul. 30, 1997 wherein the weighing device is supported by the second supporting means. Since the weighing device herein rotates, special provisions are necessary to prevent unintended torsion of the cable means which connect the weighing device to central control means. Since the weighing device is disposed fixedly in the apparatus according to the present invention, there is no question of cables subject to torsion.
The structure according to the present invention is therefore simpler than that according to the above stated Netherlands patent application. The apparatus is suitable for metering liquid or pasty masses into relatively small containers. The structure according to the invention prevents any vertical force being exerted by the drive means on the scales. Such a vertical force must be avoided since it would influence the measurement accuracy.
Driving takes place in the horizontal plane, wherein the input and the output parts of the drive element lie mutually in line.
A specific embodiment of the apparatus according to the invention has the special feature that the drive comprises at least one drive cylinder of pneumatic, hydraulic or electrical type.
A specific embodiment has the special feature that the drive comprises at least two cylinders connected mechanically in series to each other, the respective strokes of which correspond with respectively xc2xd, xc2xc, xe2x85x9, etc. of the periphery of the drive drum. This embodiment enables rapid adjustment of the angular position of the second supporting means through respectivelyxc2x1180xc2x0, xc2x190xc2x0, xc2x145xc2x0, etc. It will be apparent that any discrete angular position can hereby be realized, while the resolution is determined by the cylinder with the smallest stroke.
The invention will now be the elucidated with reference to the annexed drawings.